pulmonary system


Coelacanths are lobe-finned fishes, that look somewhat like limbs. Known from the Devonian to Recent that were long considered extinct, until the discovery of two living species in deep marine waters of the Mozambique Channel and Sulawesi. Despite extensive studies, the pulmonary system of extant coelacanths has not been fully investigated.

Since its rediscovery in 1938, scientists doubted the existence of a lung in the living species West Indian Ocean coelacanth (Latimeria chalumnae) when compared with fossil species. 

Now, an international team of researchers confirm the presence of functional lungs at early embryonic stages; these lungs lose function and become vestigial lungs in adulthood. The finding sheds light on how ancient relatives may have lived about 410 million years ago.

Coelcanths is a heavily built fish living in rocky environments between 110 and 400 m deep in the coastal waters of the Mozambique Channel and of Sulawesi. This large animal (up to 2 m long) is ovoviviparous. The young develop in the oviduct of the female, which can give birth to 26 live pups of about 35 cm long. Juvenile coelacanths (below 80 cm long) are rarely observed or caught.  

The presence of a large calcified sheath in the abdominal cavity of fossil coelacanths has been known since the 19th century but was previously regarded as either an ‘internal osseous viscus’ (unknown internal organ), a bladder or swimbladder.  Only recently this organ has been formally described in fossils coelacanths as a pulmonary organ composed of large and rounded calcified plates, positioned ventrally relative to the gut, and with a single anterior opening under the opercle.  The parallel development of a fatty organ for buoyancy control suggests a unique adaptation to deep water. 

Three-dimensional reconstructions of the pulmonary complex of West Indian Ocean coelacanth (L. chalumnae) at different ontogenetic stages.

Respiratory Anatomy

Each lung is suspended in it’s on pleural cavity ( is the thin fluid-filled space between the two pulmonary pleura (membrane sacs around the lungs))

Innervated by sympathetic (fight/flight) and parasympathetic fibres

Connected to mediastinum by lung root

Two circulations through the lungs:

  • Pulmonary - heart to lungs
  • Bronchial - systemic blood to service the lungs themselves 

September 13th, 2015
This is the cardio pulmonary vein system.
It turned out super well. Like damn. It will be so worth the tiny scraps of paper I will find all over my room for the next 2 months.

Research from the National Science Foundation refutes theories suggesting that dinosaurs had pulmonary systems more like modern-day reptiles than birds. “The pulmonary air-sac systems of dinosaurs and birds exhibit striking similarities, including predicted regions air of sac integration into the skeleton. The air sacs act like bellows to move air through the rigid lungs.”

Credit: Nicolle Rager Fuller, National Science Foundation